Self-curing Acrylic Resin Research Articles

A Comparative Evaluation of the Positional Accuracy of Multiple Implants by Open Tray Impression Technique using Three Different Splinting Materials: An in vitro study


 Aim: To comparatively evaluate the positional accuracy of multiple implants by open tray impression technique using three different splinting materials namely self-cure acrylic resin, pattern resin and flowable composite.
 Materials and Methods: An edentulous maxillary model was fabricated with heat-cure acrylic resin. Four dummy implants were placed bilaterally at canine and second premolar positions in the acrylic model, perpendicular to the horizontal plane and parallel to each other. Open tray impression copings were attached to dummy implants. The copings were splinted with dental floss onto which self-cure acrylic resin was added, which was sectioned and rejoined (for Group A). Similarly, pattern resin (for Group B) and flowable composite (for Group C) were used as splinting materials after sectioning and rejoining as previously described for Group A. Open tray impressions were made using polyvinylsiloxane impression material to obtain 10 casts for each group categorized according to the splinting material used. Interimplant distances were measured between implants on the master model and between the implant analogs in the retrieved casts in three different groups using a Coordinate measuring machine and a comparative evaluation of positional accuracy was done.
 Results: Splinting with materials of all three Groups showed minimal variation in positions of multiple implants and within clinical limits. Group B (pattern resin) had more accurate values similar to master model compared to Group A (self-cure acrylic resin) and Group C (flowable composite), although statistically insignificant. The results with Groups A and C were similar. No statistically significant difference was derived between the three different groups.
 Conclusion: It was concluded that all the three splinting materials evaluated in the study can be recommended as splinting material of choice for multiple implants using open tray impression technique.

Biomonitoring of children and adolescents using orthodontic appliances made of acrylic resins through micronucleus testing of exfoliated buccal and palatal mucosa cells

The present study aimed to investigate the occurrence of micronuclei and the degenerative nuclear alterations indicative of apoptosis and necrosis in the exfoliated buccal and palatal mucosa cells of children and adolescents using orthodontic appliances made of self-curing acrylic resins. The micronuclei and nuclear alterations were evaluated in a minimum of 2000cellscollected from the cheeks and palates of 30 patients of both sexes, aged between 6 and 12years. The cell evaluations were performed before appliance installation and 15 to 21days after installation. A conditional test was used. In all analyses, the significance level was 5%. No differences in the occurrence of micronuclei or the nuclear degenerative changes indicative of apoptosis and necrosis were observed in the cheek cells between the 2 time points (P>0.05). However, evaluation of the palate cells revealed a significant increase in the occurrence of micronuclei and the nuclear alterations indicative of apoptosis (P<0.01) but not of karyolysis (P>0.05). Direct contact of orthodontic appliances made of acrylic resins with the oral mucosa increases the incidence of chromosomal damage and degenerative nuclear alterations.

Comparison of Fracture Resistance in Thermal and Self-Curing Acrylic Resins-An In Vitro Study.

Thermal and self-curing acrylic resins are frequently and versatilely used in dental medicine since they are biocompatible, have no flavor or odor, have satisfactory thermal qualities and polishing capacity, and are easy and fast. Thus, given their widespread use, their fracture resistance behavior is especially important. In this research work, we comparatively analyzed the fracture resistance capacity of thermo and self-curing acrylic resins in vitro. Materials and Methods: Five prosthesis bases were created for each of the following acrylic resins: Lucitone®, ProBase®, and Megacryl®, which were submitted to different forces through the use of the CS® Dental Testing Machine, usually mobilized in the context of fatigue tests. To this end, a point was defined in the center of the anterior edge of the aforementioned acrylic resin bases, for which the peak tended until a fracture occurred. Thermosetting resins were, on average, more resistant to fracture than self-curable resins, although the difference was not statistically significant. The thermosetting resins of the Lucitone® and Probase® brands demonstrated behavior that was more resistant to fracture than the self-curing homologues, although the difference was not statistically significant. Thermosetting resins tended to be, on average, more resistant to fracture and exhibited the maximum values for impact strength, compressive strength, tensile strength, hardness, and dimensional accuracy than self-curing resins, regardless of brand.

Evaluation of Variation in Implant Stability Quotient at Different Time Intervals after Immediate Loading in the Posterior Mandible using Penguin Resonance Frequency Analysis System

Purpose: The aim of this in vivo study is to compare the variation in implant stability quotient (ISQ) values of implants using resonance frequency analysis (RFA) to access the immediately loaded (within 24 h) implants at different time intervals using Penguin RFA system. Materials and Methods: Ten Nobel Replace Tapered RP implants were placed in posterior mandible region of patients. Patients were included in the study after fulfilling the inclusion criteria. Prior to enrolling in the study, thorough information about the procedure was provided to the patients, and written consent was obtained for the same. Immediate loading was done within 24 h using tooth-colored self-cure acrylic resin. Penguin RFA System was used to measure the ISQ of dental implants. The ISQ values were recorded immediately after implant placement, after 4 weeks, after 8 weeks, and after 12 weeks. Results: The mean ISQ values of the immediately loaded implants at the time of placement were 82.60, after 4 weeks were 80.60, after 8 weeks were 83.70, and after 12 weeks were 87.10. There was a statistically significant difference between the ISQ values at the time of placement of implants and after 12 weeks. Conclusion: This study concluded that immediate loading in posterior mandible single tooth region is a safe and predictable option.

Evaluation of Maximum Biting Force in Two Different Attachment Systems (Bollard vs. Ball and Socket) Retaining Mandibular Overdenture: A Split-mouth Design

AIM: The study was conducted to evaluate maximum biting force (MBF) in two different attachment systems (bollard a vs. ball and socket attachment) retaining mandibular overdenture using a split-mouth design. SUBJECTS AND METHODS: Twelve completely edentulous patients received complete dentures and after adaption of the patient with the new denture, 24 implants were inserted in the canine region using two-stage surgical technique and conventional loading protocol. Six patients received the Bollard attachment at the right side and the Ball and Socket at the left side. Moreover, the other six patients received the bollard attachment at the left side and the ball and socket attachment at the right side. Each patient was treated according to split-mouth design. Insertion of each of the attachment type was assigned randomly. Using occlusal force meter instrument, MBF was measured immediately after loading (0), after 6 months (6), and after 12 months (12). RESULTS: Significant statistical differences (p &lt; 0.05) were obvious in in MBF between Attachment (1) and Attachment (2) immediately after loading (0 months), after 6 months (6) and after 12 months (12) follow-up visits. CONCLUSION: Mandibular implant retained overdenture received Bollard abutment that retained with the denture by the help of resilient liner “Retention.sil”* without housing have higher biting forces than mandibular implant retained overdenture with ball abutment where the plastic house was picked up by monomer free self-cured acrylic resin.

Evaluation of surface roughness and microhardness of enamel white spot lesions treated by resin infiltration technique (icons): An in-vitro study

Objectives This research was designed to evaluate the effect of resin infiltration material (Icon) and remineralizing agents (n-HA, CPP-ACP) on micro hardness and surface roughness of enamel white spot lesion. Materials & Methods 120 sound non carious human anterior teeth were used in this study. The teeth were divided according to the test of evaluation into two main groups. Group H: for assessment of micro hardness and group R: for assessment of surface roughness (60 teeth each).Then each group was divided into four equal subgroups (15 teeth each) according to the treatments applied as follows: subgroup(C): control, subgroup (P): CPPACP, subgroup (I): Icon and subgroup (N): n-HA. Each subgroup was further subdivided into three equal divisions (5 teeth each) according to the storage times in artificial saliva; one week (S1), four weeks (S2) and eight weeks (S3). The crowns of all teeth were separated from the roots and embedded horizontally in middle of the mould leaving the labial surface projecting using self-curing acrylic resin. Al specimens were immersed in demenaralizing solution for artificial enamel white spot lesion formation. Then treated with each respective material as follow: In subgroup (I) Icons was applied on labial surface of specimens and then immersed in artificial saliva. In subgroup (P) the labial surfaces of specimens were brushed manually by a soft toothbrush and with gentle pressure; brushing procedures were carried out three times daily with CPP–ACP- containing paste for 3 minutes then immersed in artificial saliva. In subgroup (N) specimens were immersed in 10% n-HA solution for 3min then immersed in artificial saliva and these applications were repeated daily. While subgroup (C) did not receive any surface treatment, but it immersed in artificial saliva as a positive control subgroup, artificial saliva was changed daily. For assessment of microhardness and surface roughness the enamel white spot lesion specimens in the four different subgroups were examined three times (after one week, four weeks and eight weeks from the first time of treatment application) by Vickers micro hardness testing machine and none contact profilometer. Results The results of microhardness revealed that the subgroup (N) was provided the highest micro hardness mean value, followed by subgroup (I) group, then subgroup (P) group while subgroup (C) showed the lowest micro hardness mean value.The results of surface roughness revealed that the subgroup (P) group was provided the highest surface roughness mean value, followed by subgroup (C), then subgroup (N) while subgroup (I) showed the lowest surface roughness. Conclusions Resin infiltration material (Icon) had a positive effect on microhardness and surface roughness of enamel white spot lesion.

The effect of natural reducing agents on push-out bond strength of AH plus and BioRoot RCS to sodium hypochlorite treated root dentin.

Aims:To evaluate the effect of natural anticoagulants 6.5% proanthocyanidin (PA) and 25% bamboo salt on push-out bond strength (PBS) of AH Plus and BioRoot RCS to dentin.Subjects and Methods:30 single-rooted extracted human teeth were collected. After establishing the working length samples were prepared up to size F3. 5 ml of 3% NaOCl was used as irrigant during instrumentation followed by rinse with 5 ml of 17% ethylenediaminetetraacetic acid. Samples were randomly divided into groups based on the final irrigation solution: Group I – AH plus sealer group, Ia – Saline group, Ib – PA group, Ic – Bamboo salt (BS) group. Group II – BioRoot RCS group, IIa – Saline group, IIb – PA group, IIc – BS group. After obturation, samples were embedded in self-cure acrylic resin and 2 mm thick root slices were made at coronal middle and apical 3rd. These slices were subjected to PBS testing followed by stereomicroscopic examination for checking the mode of failure.Statistical Analysis Used:Kruskal–Wallis and Dunn's post hoc test.Results:3% NaOCl significantly decreased the bond strength of AH Plus as compared to BioRoot RCS to dentin (P < 0.05). Both PA and BS were capable of increasing the PBS of AH Plus and BioRoot RCS to NaOCl-treated dentin.Conclusions:Final irrigation with antioxidants such as PA and BS eliminates the risk of reduced bond strength of sealer to root canal walls, which ensues following the use of NaOCl as an irrigant.

Resistência de união ao cisalhamento entre a resina composta e dentes artificiais de resina acrílica

Acrylic denture teeth may suffer fracture or wear requiring the need for repair. This study aimed to evaluate the shear bond strength between acrylic resin artificial teeth restored with composite resin (with two different surface treatments) and acrylic resin (AR), simulating repair with these materials. Thirty artificial incisors were included by the palatal side in a circular microwave-polymerized AR base and polished on their buccal side with 120 and 320 grit sandpaper in a metallographic polisher and, then, divided into three groups: (I) restoration with self-cured AR; (II) conventional restoration with Z-100 composite resin with application of acid etching and Single Bond-3M adhesive; and (III) restoration with Z-100 composite resin with submersion for 30 seconds in acetone and application of Single Bond-3M adhesive. Shear bond strength tests were performed in a Universal Testing Machine (Instron). The results were submitted to ANOVA and Tukey (p&lt;0.05) tests, in which Group I (33.26MPa ±10.76) and Group III (22.24MPa ±13.13) showed no statistically significant difference, but both were superior to Group II (10.31MPa ±5.62), which showed a lower value of shear bond strength. It can be concluded that composite resin restoration with acetone pretreatment can be a viable alternative for repair.

Evaluation of different custom angulated elastic glass fibre post on fracture resistance of maxillary central incisor: an in vitrostudy

Background: Restoring Endodontically treated teeth (ETT) can be challenging for most dentists, particularly when a significant tooth structure is lost. Depending on the coronal tooth structure remaining and the technique used (direct or indirect), endodontic anchorage can involve either a cast post and core or a prefabricated post. Aim: This study aimed to investigate the effect of different custom angulated, i.e.,0°,5°,10°,15° elastic glass fibre post (Everstick post) on fracture resistance of maxillary central incisors. Materials and methods: A total of forty-eight single-rooted maxillary central incisors were selected. All the samples were decoronated 2mm above the CEJ and endodontically treated. Post-space preparation was done for all the samples using peesoreamers ranging in size from 1-3. The samples were then randomly divided into four groups (n=12) based on the different angulations, i.e., the angle between the core and the long axis of the root, with 0°, 5°, 10°, and 15° angulations, respectively. The fit of each post in the root canal was verified. Before cementation, the coronal part of each post was bent according to their respective groups. Dual-cure resin cement was used for luting the posts and cured subsequently. The fracture resistance of all the samples was evaluated using the universal testing machine after they were mounted in self-cure acrylic resin blocks. The data were analysed using One- way ANOVA and Tukey’s post-hoc test. Results: Group I exhibited the highest mean fracture resistance compared to other groups. However, One-way ANOVA showed no significant differences (p=0.161) between the four groups. Conclusion: Everstick fibre posts are a preferable alternative for maxillary central incisors with core angulations up to 15° between coronal and radicular segments as they provide better fracture resistance with a more favourable stress distribution.

Comparative evaluation of shear bond strength of a dual-cure core build-up composite bonded to dentin using three different self-etch dentin bonding systems - An in-vitro study

Aim: This in-vitro study compared the shear bond strength of a dual-cure core build-up composite bonded to dentin using a two-step self-etch adhesive, with two, single step self-etch universal adhesive systems. Materials and Methods: In the present in-vitro study, sixty extracted permanent human mandibular molar teeth, decoronated below the dentino-enamel junction to expose the coronal dentin, were taken and later mounted in self-cure acrylic resin. The specimens were randomly divided into three groups of twenty samples each, based on the dentin bonding agents used namely ParaBond (a two-step self-etch adhesive) and two one-step universal adhesives i.e. Single Bond Universal and Tetric N-Bond Universal. The dentin surface of samples was treated with the respective adhesives of the groups according to manufacturer’s instructions. The bonded surface was bulk filled using ParaCore dual-cure composite. The attained samples were stored in distilled water at 370C for 24hrs and subsequently put through thermocycling (50C to 550C for 500 cycles). The samples were than subjected to shear loading in Instron Universal testing machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA) and Tukey’s HSD test. Results: Tetric N-Bond Universal adhesive showed the highest mean Shear Bond Strength (SBS) of 20.78 MPa, followed by Single Bond Universal 19.07 MPa and ParaBond Adhesive 5.44 MPa. Conclusion: Tetric N-Bond Universal showed the highest mean SBS and a predictable relationship was found between the formulation of dentin adhesive systems and their shear bond strength values. Clinical Significance: The universal adhesives showed high shear bond strength as compared to conventional 2-step self-etch adhesives. High acidic pH of self-etch adhesive affected their bond strength. So for stake of bond stability, a mild self-etch / universal adhesive is recommended for adhesion, because higher the bond strength, higher it can withstand the stress

The difference of surface roughness in acrylic resin self-cured with addition of zirconium dioxide particles as a denture repaired materials

Background: Tooth loss is one of the effects of periodontal disease and dental caries. Tooth loss can be resolved by making a denture prosthesis. Several factors that influence society on denture use include aesthetic, social, func-tional, educational, and cultural factors. The large number of lost teeth will certainly increase the demand or desire to manufacture dentures to restore the function of the missing teeth. One of the materials that are often used in den-tures is acrylic resin. Acrylic resins frequently used for denture base materials are cold polymerized acrylic resin and hot polymerized acrylic resin. Cold polymerized acrylic resin uses chemical activation, and this type of resin is often used for denture repair materials. Denture repair aims to repair prostheses that have many fractures in the mid-line area. Chemical polymerization acrylic resin is often used as a repair material because it is easy to apply and can be done directly on the patient. This resin has a disadvantage because it often leaves residual monomer in the polymerization process, so it impacts porosity. This problem can be overcome by modifying the resin's chemical structure using polyethylene glycol or by adding ZrO2. Objective: This study aims to determine the effect of adding 3%, 5%, and 10% of zirconium dioxide (ZrO2) nanoparticles to the surface roughness of self-cured acrylic resin as a denture repair material. Methods: Four sample groups, each consisting of 10 samples, were divided into the con-trol group (K), the treatment group with ZrO2 addition 3% (P1), the treatment group with the addition of ZrO2 5% (P2), and the treatment group with the addition of ZrO2 10% (P3). The results of all treatments and controls were tested for surface roughness using the MST-301 surface roughness test profilometer. Results: Based on the results of the descriptive test, the mean of group K = 0.395 ± 0.161, group P1 = 0.813 ± 0.525, group P2 = 1.284 ± 0.336 and group P3 = 1.093 ± 0.558. In the Kruskal-Wallis test, there were significant differences in all groups. Conclusion: The self-cured acrylic resin with the addition of 3% concentration of ZrO2 has the lowest surface roughness com-pared to the other groups, and the roughness is almost similar to the surface roughness of the control group.

Surface Microstructure Study of Self Cured Acrylic Resin after Immersion in Arabica Gayo Coffee

The water absorption on self-cured acrylic resin is higher than the heat cured acrylic resin. Incoming water positions itself between the polymer chains and affects the surface microstructure of self-cured acrylic resin. The absorption of liquids such as Arabica Gayo coffee may aggravate the surface structure of self-cured acrylic resins due to their acid content. This study aims to find out the microstructure of self-cured acrylic resin surface after immersed in Arabica Gayo coffee for 2 and 7 days. This study used 5 specimens of self-cured acrylic resin (MeliodentTM) with size 10x10x1,5 mm3. Each specimen was immersed in aquades for 24 hours to reduce the residual monomer and then be given different immersion treatments. The immersion temperature used was 55°C. After immersion, surface microstructure observation was done using Scanning Electron Microscope (JEOL JSM 6510 LA). The images obtained were bubbles after being immersed in aquades for 2 days and more on day 7, micro porous after being immersed in Arabica Gayo coffee for 2 days and more on day 7 than untreated specimens. The conclusion of this study is micro porous formed more on the surface of self-cured acrylic resin along with the duration of self-cured acrylic resin immersion in Arabica Gayo coffee.

Effect of silica nanoparticles on mechanical properties of self-cured acrylic resin

The purpose of this in vitro study is to evaluate the effect of the incorporation of silanized and non-silanized silica nanoparticles (~ 160 nm) in mechanical properties and surface roughness of self-cured acrylic resins. Five groups of samples were produced (with six specimens each), following the ISO 20795-1:2013 specifications. In the control group (Ctrl), no particles were added in the resin composition. Non-silanized silica nanoparticles were added either into the polymer (0.7 wt%, group G1) or into the monomer (0.27 wt%, G2). Two equivalent groups were formed for composite resins with silanized nanoparticles (groups G3 with 0.7 wt% incorporated into the polymer and G4 with 0.27 wt% added into the monomer). Data were submitted to Shapiro-Wilk (α = 0.05) and ANOVA/Tukey (α = 0.05). Nanoparticle-loaded resins showed similar microhardness as the control and a reduced flexural strength (20–27%) which was neither dependent on the amount of filler added nor in the method of nanoparticle incorporation. Surface silanization caused no major improvement in the mechanical behavior of the nanoresins but appears to improve dispersibility, as indicated by a smaller surface roughness.

THE EFFECT OF A VARNISH CONTAINING SELF-CURING RESIN ON THE SOFTNESS OF TWO TYPES OF TISSUE CONDITIONERS

Objectives: One of the limitations of tissue conditioners (TC) is the gradual hardening of the material in a short time after insertion in the mouth. This study aimed to determine the softness of two different tissue conditioners with and without the coating made up of 1,1,1trichloroethan and self-curing acrylic resin.Materials and Methods: In this experimental study, Acrosoft (Marlic, Tehran, Iran) and GC (GC corporation, Tokyo, Japan) tissue conditioners were examined. 28 discs of 20 x 3 mm dimensions were prepared for each tissue conditioner (n=14). Half of the samples in each group were coated with varnish coating made up of 1,1,1trichloroethan and self-curing acrylic resin. The hardness of all samples was measured at five intervals of 1,3,7,14, and28 days by a Shore-A Durometer with a conical indenter. The data were analyzed by descriptive statistics and Friedman analyses. P&amp;lt;0.05 was considered statistically significant.Results: The mean hardness of the GC and Acrosoft tissue conditioners on days 1, 3, 7, 14, and 28 in both varnish-coated and non-varnish-coated groups were statistically different and Acrosoft tissue conditioner was harder than the GC. In the paired mean hardness comparison on days 1, 3, 7, 14, and 28 in the GV and G0 groups: this trend was the same in AV and A0 groups. The comparison of hardness in the GV and G0 groups at each time interval indicated that only on day 3, the control group(G0) was harder than the surface coating group(GV). The comparison of the hardness in the AV and A0 groups showed that on days 3 and 7, the hardness in the control group (A0) was higher than the surface coating group(AV).Conclusions: The varnish containing self-curing resin can soften the Acrosoft and GC tissue conditioner in a short time. Moreover, this varnish can be clinically applied in the borders between the soft liner and acrylic denture, which is usually the starting point for debonding.

Management of caries affected dentin (CAD) with resin modified glass ionomer cement (RMGIC) in the presence of different caries disinfectants and photosensitizers.

To evaluate Shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) on caries affected dentin after using different cavity disinfectants i.e., chlorhexidine gluconate (CHX), Er,Cr:YSGG laser (ECYL) and photodynamic therapy (PDT). Total 50 freshly extracted mandibular molars were obtained through non-traumatic extraction. All the samples were rooted vertically within self-cure acrylic resin blocks up to cervical level so that only coronal portion remain visible. Silicon carbide grinding discs 1200 and 600 grits was used to prepare the teeth. However affected dentin remains untouched. All samples were randomly distributed in to five groups (n = 10). Group 1: 2 % CHX, Group 2: 2 % solution of methylene blue (MB) and Diode laser, Group 3: Indocyanine green (ICGP) solution and Diode laser, Group 4: curcumin (CP) and LED curing unit, Group 5: ECYL. The specimens were then stored at a temperature of 37 °C for 24 h and 100 % humidity before specimens were placed in to universal testing machine for the SBS measurements. Failure mode examination was performed by a stereomicroscope. ANOVA test analyze inter group comparison. Tukey HSD test was used to analyze multiple group comparison. The level of significance was set at p < 0.05 value. Among all the groups, group 1 (control, CHX treated) demonstrated highest SBS value (18.31 ± 1.06 MPa). Whereas lowest SBS was displayed by group 2 (PDT, MB) (12.31 ± 0.57 MPa). Dentin disinfected with group 4 (PDT, CP) (16.86 ± 0.97 MPa) and group 5 (ECYL) (17.39 ± 2.26) showed comparable result to that of CHX (p > 0.05). Bond strength of RMGIC bonded to CHX disinfected caries affected dentin was highest among study groups. Use of MB showed lowest shear bond strength outcomes. Moreover, application of ECYL and curcumin with LED showed bond strengths comparable to CHX control.

The Analysis of the Differences between the Influence of Herbal Mouthwashes and the Chlorhexidine Mouthwash on the Physical Characteristics of Orthodontic Acrylic Resin

The present study, intended to compare the effects of immersion in herbal mouthwashes and the Chlorhexidine mouthwash on orthodontic acrylic resin, specifically with regard to alterations in its hardness, roughness and color. Seventy-two specimens of Orthodontic self-cured acrylic resin were used for the experiments. After preparation, specimens were placed in three types of mouthwash including Chlorhexidine 0.2 % (CHX), Persica and Matrica. The changes in microhardness (ΔKNH), Surface roughness (ΔRa) and color (ΔE) were evaluated prior to and following the immersion in mouthwashes. In order to analyze the data, we made use of SPSS version 22. One-Way ANOVA test was used to find the differences between groups. The Tukey test was conducted in the final stage. It was revealed that acrylic resins had lower microhardness when 12 hours after immersion had taken place. There were significant differences after 12h, 24h and 7 days between the groups in the softening of acrylic resins. The reduction in microhardness of acrylic resin with herbal mouthwashes in the three-time intervals was higher than CHX. With regard to increasing surface roughness, the disparity between herbal mouthwashes was insignificant. However herbal mouthwashes significantly increased the value of roughness more than CHX. Changes in color were significantly higher in all mouthwashes. Herbal mouthwashes caused more color variation than CHX. The color, roughness and hardness of acrylic resin undergo changes as a result of being immersed in the mouthwashes. However, the effect of herbal mouthwashes was more than that of CHX.

Theatrical Prosthesis – Widening Horizons of Prosthetic Dentistry – A Case Report

A movie or a play is said to be great if it can imprint an image in our mind forever. To accomplish this, even the unnatural looking characters should look real. This case report describes a temporary prosthesis which alters the look of a theatre artist suited as a Dracula. Mock wax-up was done on the stone cast and an index of same was made using putty material. After dewaxingof the cast, tooth colored self-cure acrylic resin was mixed and poured into the index and stone cast with separating medium applied over it was pressed into the index. Prosthesis was retrieved, trimmed, polished and then delivered to patient.

TOOTH PREPARATION WITH HIGH C-FACTOR UTILIZING VARIOUS METHODS AND MICROLEAKAGE

Introduction Composite Resins have been used for nearly 50 years and year after year improvements have been made regarding their composition and their handling properties. The use of this material has been continually increasing because of ability to bond to dental structure, its high aesthetics and conservative preparation. Aims And Objectives A. Evaluation of the marginal microleakage of Class-I cavity preparations (i.e. high C-factor preparation) restored with different composite placement techniques. B. Find the composite placement technique which is able to eliminate marginal microleakage in tooth preparations with high C-factor Methodology 120 human premolar teeth , recently extracted, free from caries should not have other structural defects. A. Materials: Normal saline, Self-etch Adhesive system, Nano-hybrid composite Distilled water, Enamel varnish, Selfcure acrylic resin, 0.5% solution of Methylene blue dye, B. Armamentarium: Airotor handpeice. Micromotor Contrangle handpeice. C. Equipment used: LED Curing light, Thermocycling machine, Stereomicroscope Observations And Results The microleakage scores for the six different resin composite placement techniques. The score was subjected to Kruskal-Wallis test for the comparison among the six experimental groups (P< 0.05, it indicates significant difference. it indicates highly significant difference among different groups. But here P=0.16 this indicates no statically significant difference among the six groups. On comparing Group I with Group VI, the P value is = 0.52, so the difference is not statistically significant. On comparing Group II with Group VI, the P value was = 0.52, which is more than 0.05, so the difference is not statistically significant. On comparing group III with Group VI, the P value was = 0.20 so the difference is not statistically significant. On comparing Group IV with Group VI, the P value was = 0.75, so the difference is not statistically significant. On comparing Group V with Group VI, the P value was 0.11, which is more than 0.05, so the difference is not statically significant. Conclusion Within the limits of the present study concluded that, none of the techniques for resin placement was able to eliminate marginal microleakage in Class-I cavity preparation. The complete control of marginal microleakage in tooth preparation with high C-factor still presents a challenge

Comparison of the accuracy of fixture-level impression making after splinting prosthetic components

Considering the effects of different impression-taking techniques on the dimensional accuracy of the final cast and controversies over the best technique in implant dentistry, the present study was undertaken to evaluate the effects of three different open-tray impression techniques on the dimensional accuracy of final casts for implants. A two-piece metallic index was prepared and a patient’s jaw was simulated by placing self-cured acrylic resin in the lower part of the index. Then 2 holes were produced in the acrylic resin at a specific distance from each other, and the analogs were placed in these holes. Three different open-tray impression techniques were evaluated using the upper segment of the index, which mimicked the specific tray. The dimensional accuracy of the casts was evaluated by comparing the distances between the predetermined points on the implant analogs and the positions of the points with similar distances on the master model. A digital caliper (accurate to 0.01 mm) was used to measure the distances. The differences in the measurements on the final casts were analyzed with SPSS 16, using Kruskal-Wallis test. Post hoc Mann-Whitney U test was used for two-by-two comparisons. There was a significant difference between the group in which the analogs and impression copings were not splinted and the group with impression coping splinting without analog splinting and the group with simultaneous splinting of the impression copings and implant analogs, in relation to distances between similar points on the master model. In this context, the second and third techniques better reconstructed the positions of the points. Splinting of impression copings with Duralay acrylic resin prevented the movement of impression copings during the impression-taking procedure and despite an increase in the accuracy of impression taking during splinting of analogs by Duralay acrylic resin, the increase in accuracy was not significant statistically; therefore, splinting of the impression copings without splinting of the analogs is recommended due to an increase in impression-taking accuracy and facilitation of laboratory procedures.

Chairside fabrication of provisional crowns on FDM 3D-printed PVA model

PurposeThe purpose of this study was to evaluate the dimensional accuracy of crowns fabricated using a polyvinyl alcohol (PVA) dental model. MethodsAn intraoral scanner (LAVA TDS) was used to scan a prepared molar abutment as a master model. The STL file obtained from the scanning process was transferred into the FDM 3D printer (Value 3D Magix MF-1000) and then models were fabricated with PVA filament. In order to compare with the conventional method, an impression of the master model was taken using silicone impression material to fabricate the conventional stone cast model (Conv). An indirect resin composite (Gradia) and self-cured acrylic resin (Curergrace) were used to fabricate crowns (n = 20) according to the manufacturer's instructions. Surface accuracy of the Conv and PVA models and internal accuracy of the crowns set on the models were measured using two methods; 3D digital analysis and silicon-fitting evaluation. Statistical analysis of the results was done using t-test and Willcoxon signed rank test with Bonferroni correction at 5% significance. ResultsDigital analysis showed the Root Mean Square (RMS) value of PVA model surface was higher than that of Conv, while there was no significant difference between the two crown materials. However, the silicon-fitting analysis showed marginal discrepancy of crowns fabricated on PVA model were within 100 µm. Conclusion3D printed PVA model can be used for chairside crown fabrication with an acceptable accuracy.